THE demonstration in Oxford two weekends ago at which 600 people expressed their support for animal testing could have big implications for scientific research. Medical students, researchers and scientists, previously reluctant to speak up for fear of intimidation and harassment, took to the streets in response to protesters who are campaigning against a new animal research facility at the University of Oxford.

The march was organised by a new group that goes by the catchy title of Pro-Test. Their message that research on animals is necessary and justified sounds simple enough, but is it too simple? Like other debates in bioethics, this one is characterised by a stark polarisation of views. At first glance, it seems to offer only two options: either you're for animal research, or you're against it.

There are many reasons for this polarisation. The issues are highly emotive, and people are often reluctant to negotiate. An adversarial for-and-against style of debating is deeply ingrained in political and media worlds. And organisations that oppose animal research need to raise funds for their campaigns and believe that only a decisive message is likely to win public support.

Is there anything wrong with having a polarised debate? A great deal. It is simplistic. It is often dishonest. It also prevents progress: while polarisation may serve campaigners, politicians and some activists, it makes it very difficult for lay people to form reasoned opinions about the issues.

Take, for example, one of the Pro-Test group's main themes: No animal research = no medical progress. Can it really be that simple? It raises a host of questions. Do they mean that it's OK to use any animal, and any number of them, and in any way, if researchers deem it necessary? If not, how should we decide what is acceptable?

These are complex issues that demand greater attention. Is it as acceptable to use animals to satisfy scientific curiosity, such as investigating basic physiological processes, as it is to test a new cancer treatment? If scientific progress is the key justification, what counts as progress? A published paper? A new cure? In any case, only one-third of research on animals is for medical purposes. Is it acceptable to use an animal to test the safety of a new plant insecticide? Being a Pro-Tester is not as straightforward as it seems.

It is just as complex for those radically opposed to animal research, if you look closely enough. They frequently claim that no research has ever been useful, even that it is dangerous to humans, and that it is ethically unacceptable as it causes suffering. Yet many animal protesters themselves benefit from medical techniques developed using animals, and not all research causes suffering.

If the previous paragraphs leave you confused, you are in good company. These issues have confused people who have thought long and hard about them. We were part of such a group, as members of a working party of the UK's Nuffield Council on Bioethics set up to look at the pros and cons of animal testing. The 18-strong committee included campaigners who were fundamentally opposed to such research and those who defended it, as well as academic and industry scientists and philosophers.

The group's report, published last year, set out a number of recommendations for policy and practice, which the council is currently following up. We suggested several ways of improving the quality of the debate, which is crucial if we are to make progress. For instance, it would help if government statistics on animal research were more transparent and better explained so members of the public could understand what they mean. It remains too easy for both sides to use the statistics to support their polarised views.

We also recommend holding more public debates on the issues - through focus groups, citizens' juries and the like - so that people's views are properly heard. In addition, those involved in research should enter into dialogue with the public and explain about the intended benefits of their work, and what it means for the welfare of animals involved. You may well ask how researchers can enter such a dialogue under the threat of violence from extremists. But the more people speak up in a reasonable manner and engage the public in a proper debate, the less tenable the extremists' tactics will be.

Polarising the debate is counterproductive for both sides. Peaceful protests for and against animal research are legitimate ways of contributing to informed debate, but they must not be an end in themselves. We fully commend those who joined the Pro-Test campaigners for putting their heads over the parapet, but we hope they pay close attention to this. Simplifying the debate in the same way that those opposing animal research have done is just plain unhelpful.